I took was a have BB user, though BIS, never with exchange. Own a small biz, all of us get mail via pop using outlook.
With droid, here are the following options I have found.
a)your mail hosting site probably offers excahnge hosting for about $10/mo. My hosting company allows for a mix of pop and exchange, so if only a few want exchange, the rest can use pop. So you can set yourself up on exchange and droid does this fairly well.
b) i set up a forward for a pop account just for droid. That way I have my outlook getting messages and my droid as well. They are not sync'd, i just don't lose anything and have duplicates on both. If this is not good, you need exchange.
c)k-9 mail seems to work great for pops.
d)what i miss right now is that my outlook contacts, calendar and to do don't sync to the droid. There are a few apps coming out next month that promise to do this. You can do this via gmail sync, but it's cumbersome.
Bottom line is that if you are dependent upon your phone for email, instantly, the droid doesn't cut it unless you can use gmail. That is not an option for me, but then again I am not wholly dependent upon email.
In every other category, the droid beats the BB IMHO.